Generally, you need a quarter inch per foot. This is for the floor....I go a bit more as I like to see the water fairly "Rush" to the drain. Having said that, his slope is a bit excessive, but not unduly so. Half of that would have been adequate.....but if the leaning shampoo bottles don't bother you, don't worry. Better more than less. ALL horizontal surfaces.....curb, niches, benches need to slope in towards the drain.

Thanks so much, stonetech! Maybe this will keep me from stacking things there in front of my beautiful glass wall, anyway. I am getting used to how it looks.

For a half-wall cap piece that will support glass, I want the cap flat where the glass will bear upon it.

In your case where one side is wet, I'll bevel that side. If the cap is 6" wide, about half the width, or about 3", will be beveled. Shaving it down about 1/8" over those 3" gives an effective pitch of 1/2" per foot of run. Plenty enough for drainage.

This drawing is intended for door thresholds, but the profile is roughly the same. If your cap was 6" wide and 1" thick and you wanted the glass roughly centered on the cap, I'd start the bevel about 2-3/4" from one edge and take it down so the beveled edge is 7/8" thick.

{{gwi:1500919}}

Oh shoot! That bevel makes a lot of sense, but I of course didn't ask the fabricator to do it that way. Given that the piece is flat, should I just keep it on the
angle it's already on? Or do you think the shower installers can compensate when they put in the U-Channel?

I'd ask the glass installers. Tell them that it's pitched 1/4" over 6", or the equivalent of 1/2" per foot.

The slope could create issues depending on the channel they use and how they intend to secure the channel to the cap.

Thanks mongo!

Shower guy gave a thumbs up; seemed to think angle was not quite what I calculated.